Polyesters containing functional groups are a suitable candidate matrix for cell culture in tissue engineering. Three types of semicrystalline copolymer poly(
Multiple synthetic biopolymers including polyglycolic acid, polylactic acid, poly(lactic-co-glycolic acid) (PLGA), and poly(caprolactone) are used as biomedical polymeric materials in tissue engineering and drug delivery because of their good biocompatibility and biodegradability [
Copolymerization between functional monomer and polyester matrix introduces functional groups, through which a small peptide can be bonded onto the polymer. This method can promote cell growth and differentiation [
In this study, the cyclic monomer 3(S)-[(benzyloxycarbonyl)methyl]-1,4-dioxane-2,5-dione (BMD) was used for ring-opening polymerization with
Benzyl alcohol (C6H5CH2OH), ethyl alcohol (CH3CH2OH), ether (CH3CH2OCH3CH2), ethyl acetate (CH3COOC2H5), dodecanol (C12H25OH), pyridine (C5H5N), sodium bicarbonate (NaHCO3), and sodium nitrite (NaNO2) were purchased from Guangzhou Chemical Reagent Factory (China).
The mole ratio of
BMD was synthesized using
Sn(Oct)2-catalyzed ring-opening polymerization of BMD with
Copolymers with protecting groups (2 g) were dissolved in trifluoroacetic acid (20 mL). Briefly, 33% HBr/CH3COOH solution (8 mL) was added dropwise under Ar atmosphere after the complete dissolution of the copolymer. The product was poured into anhydrous ether (200 mL) after 5 h at ambient temperature. The precipitates were dissolved in chloroform and purified by ethanol.
Copolymers after deprotection (2 g) were dissolved in chloroform (30 mL). NHS (3 mmol, 0.6 g) and DCC (3 mmol, 0.34 g) were added dropwise. The compounds were reacted for 2 h in an ice bath and for 24 h at room temperature. The product was dissolved in ethanol and precipitated with chloroform.
The polymer films were prepared by solution pouring and solvent evaporation. The samples were then immersed in 1.0 mg/mL short-peptide solution after drying. The film was then soaked for 12 h with mild agitation and washed three times (once per hour) with phosphate-buffered saline (PBS) solution to remove unreacted short peptides.
The polymer film functionalized with peptide on 15 mm cover slip was placed in a 24-well plate and pressed with ring to ensure complete contact of the scaffolds to the wells. The specimens were sterilized under UV light, washed three times with PBS, and immersed in Dulbecco’s modified Eagle’s medium (DMEM) overnight before cell seeding. Rat pheochromocytoma-derived cell line (PC12) was seeded on the film at a density of 1.0 × 104 cells/well and cultured in DMEM containing 10% FBS, heat-inactivated fetal bovine serum, and 1% penicillin
The cell-cultured films were processed for SEM studies 5 days after cell proliferation. The scaffolds were washed twice with PBS and fixed in 3% glutaraldehyde for 3 h. The scaffolds were then washed with deionized water and ethanol (50%, 70%, 90%, and 100% concentrations) twice for 15 min each. Finally, the films were coated with gold and observed by SEM analyses.
The results of the 1H NMR spectrum and GPC test showed the successful synthesis of the copolymer poly(
Polymerization of
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Δ |
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100/0 | 100/0 | — | — | — | 60.8 | 177.2 | 93.6 |
98/2 | 98.0/2.0 | 1.0 × 105 | 1.6 × 105 | 1.03 | 55.9 | 162.4 | 55.6 |
95/5 | 95.4/4.6 | 1.0 × 105 | 1.1 × 105 | 1.12 | 53.7 | 154.2 | 54.8 |
92/8 | 93.6/6.4 | 1.0 × 105 | 1.0 × 105 | 1.19 | 53.4 | 147.4 | 9.4 |
1H NMR spectrum of P(LA92-
Figure
Infrared spectra of (a) BMD and (b) after ring-opening polymerization.
The
Gel permeation chromatography traces of the obtained P(LA-
The thermal properties of the copolymers were investigated by DSC measurement (Figure
Differential scanning calorimetry thermograms of the obtained P(LA-
The SEM images of the PC12 cells after 5 days of seeding are shown in Figure
Scanning electron micrographs of PC12 cells seeded on the copolymeric films 5 days after isoleucine-lysine-valine-alanine-valine linking.
In this study, a series of P
The authors declare that they have no competing interests.
This work was supported by the National Youth Science Fund (81401787), the National Natural Science Foundation of Guangdong, China (2015A030310353, 2015A030310345), and the Science Program of Huizhou University (20141111103042712).